Economizer



5 Sheets-Sheet 1 ECONOMIZER J. H, SENGSTAKEN Filed May l5, 1954 1 I m n rw w n r n w l n l July 9, 1935.

INVENTOR L///V /L :SE/VQSTAKE/V. BY m ATTORNEY July 9, 1935.

J. H. SENGSTAKEN ECONOMI ZER Filed May 15,A 1954 3 Sheets-Sheet 2 ZGJ/c.

ATTORNEY July 9, 1935. .1. H. sENGsTAKEN 2,007,309

` ECONOMIZER Filed May l5, 1934 3 Sheets-Sheet 5 INVENTOR l L/o/f/V H. fVGS/IKEM BY f.' (7m ATTORNEY Patented July 9, 41935 om@ STAT EcoNoMizEa John H. Sengstaken, Plandome, N. Y., assigner to The SuperheaterCompany, New York, N. Y.

Application May 1,5, 1934, serial No. 725,765

17 Claims.

` `The present invention relates to fluid heaters and more particularly to. those having serpentine units and to be employed for boiler economizers. ...Heaters intended for use as economizersre- 5 quire, for economic reasons, to have a high rate iii) of 'heat absorption per vcubic foot of heater volumeand therefore a large amount of heating .surfacerper cubic foot. The pipe runs of econovinizers, however, need to be'inspected and cleaned from time to time and hence need to be connected in largemeasure by breakable joints. In spitefof `certain advantages of a bare tube economizrer as compared to an extended surface economizer,` it hasbeen found diiiicultv to introduce sufficient Vheating surfaceV per cubic foot into av bare tube design of economiser because ofthe room required for-the joints. mizer varies iii-temperature and so also do the heating gases, so that the breakable jointsv in such structures are liable to; develop leaks due to "differential expansion and contraction of the parts.- As a result of experience, many econo.- mizers have their breakable jomts of the multibolt flanged type. The flanges of such joints, however, occupy considerable space and have 'thereby limited the spacing of the tubes of the lunits and thereby also the surface of bare tubing `per cubic foot to the disadvantage of the bare tube design.' f

:It is an object ofmy'invention to provide a Vdesign of heater or economizer structure adapted to absorb a large amount of heat per unit volume of flue space even with only bareY tubes and without extended surfaces.- A further object of -my inventionis to provide a heater design adapted to include a. multiple bolt type of joint to insure against leaks.

In order that my invention, together with its objects and advantages, may be fully and readily understood, I will now describein detail and in vconnection with the accompanying drawings, two

exemplications of my invention selectedl from a number of possible embodiments thereof. In the drawings,

Fig; i is a sectional elevation through one form of heater in accordance with my invention.

- Fig. 2 isan end View, partly in section, of the heater shown in Fig. l, the sectioned portion be- 'ing takenon the line 2-2 of Fig. l. 'j

Fig. 3v is an elevation partly in section taken cnthe line 3'--3 ofFig. 1.

Fig. 4 is a sectional elevation of a second form 'of heater in accordance with my invention.

Fig. 5v is an `end elevation partly in section L Ltaken on lline 5--5 ofFigA.

The water passing'to an econo- Fig. 6 is a portion offan end elevation -partlyY in section taken on line B-I of Fig. 4.

Fig. '7 is an enlarged detail of some of the end connections appearingin Figs. 1 and 2. f Fig. 8 is a view taken at right angles to Fig. V'7, parts being broken away to illustrate Ythedetails of thevjoint. Y

Fig. V9 is an enlarged detail of some end con nections. appearing in Figs. 4 and 5.

Fig. 10 is a vievr taken at right `angles to Fig. 9. )The heater illustratedin Figs. l, 2 and 3 comprises vertical plates Ill andIDa dening a flue I2 which 'are mounted a considerable'number of serpentine units I-4, shown each in a'given vertical plane. Fluid to be he'ated,for instance boiler or feed water, is'conducted -to the inlet ends of Vsaid units I4 through a header I6. Fluid Vwhich has been heated in units I4 isi delivered by them into an outlet header I8. In the arrangement shown, each of the Ill includes a plurality of straight tube runs 2U, 20 whichare illus- ,tratedas lying horizontally. Each tube run 20 extends through both the plate I and plate Illa. 4For most of its length, each such run is composed vof a plurality of tubesY 2 I, 2l arranged to conduct `'fluid therethrough in parallel. Nearat leastone ,fof its ends, each tube run 2D is, at a point in flue I2, reduced to a single tube section 2 Ia which extends through one of the plates II), Illa.r As illustrated, thev single tube sections Zia all extend through the plate I0. In the arrangement illustrated in Figs. l, 2 and 3, the plural tube runs 20 forming the major portions or .sections of units 'M .each have three tubes 2l in parallel. However, I do not limit myself to any particular numf; ber of tubes in parallel in such portions ofthe apparatus altho I prefer to use either two or three.

At the ends of the runs 2) nearer the supporting plate Illa, the tubes of such runs are'connected in pairs by return bends 24, 2li, preferably y.10 ofthe integral type, so'that the units illustrated are formed of a plurality of U-loops. On the outside of the plate Il), the single tube sections '21a` at the ends of the-runs are connected by removable return bends 26, v26 and 21, 21. Bends V26 have different lengths and different spans than the bends 21 because alternate loops have a -slightly diierent arrangement.' As appears in Fig. 2,'the three tubes 2| of each run 20 are set so that their centers form a triangle, the center of one tube lying on the central vertical planeof the unit and the other two on opposite sides of such plane. However, alternate'runs 20 of each horizontal row of runs of units I4 have the tubes Yon theircentral Vertical planes atV the `top sides 4of the runs and alternate runs have the tubes on their central planes on the bottoms of the runs. By making some units with their top runs 20 of one arrangement and some of the other, and assembling the units so that one arrangement alternates with the other across the width of the heater, the tubes 2| are given the same horizontal spacingthroughout each horizontal row; that is, the horizontal distances between centres is the same between a pair of tubes of adjacent units as between a pair of tubes of a given unit, as clearly shown in Fig. 2. The single-tube end sections 2Ia of alternate units I4 are connected by the removable return bends 26, and sections 2Iaof the remaining units are connected by removable bends 21.

In order to ensure against leaks at the bends between the removable return'bends and sections 2 Ia, I employ bolted flange joints to connect such parts and preferably employ three-bolt joints. 'The 'flanges for such joints appear at 28 and 29 of Fig. 1, flanges 28 being carried by the ends of the removable 'Us 26 and 21 and the flanges 29 being carried by the single-tube end sections 2 Ia. lFlanges 29 need to be removable andare shown `as threaded onto parts 2Ia. Flanges 28 canbe fixed on bends 26 and 21 by weld metal as shown `il so desired. The three-bolt flange joint is very reliable because it 'eliminates any tendency to tilt about the line joining the bolts, as occurs in twobolt flange joints. However, I do not limit myself in all cases to the use of three-bolt joints, as at times I may use two bolt flange joints, or joints lof any number of bolts more than one. Preferably I prefer to employ a gasket 30 as shown at the detailof the joint appearing in Fig. 8. However, Ido not limit myself to this and it will be understood that I do not claim to have originated the joint; illustrated in Fig. 8, or the three-bolt flange construction. However, such a construction requires relatively more space at the side or 'sides of the economizer where the removable `return bend is employed than does the two bolt flange arrangement. Due to the space saved by the use of single-tube end sections for the tube runs, I am,.however, able to employ the threefbolt flange joint and still obtain the large amount -of ybare tube surface per cubic foot of flue volume needed to .improve the competitive position of -the bare tube design of economizer. The three -bolt flange naturally leads to flanges of the form of equilateral triangles as shown.

It will be seen that, in spite of the three bolt `flanges illustrated, tubes 2I are set, except where space is provided for tube cleaners or blowers, less 'than two diameters apart between horizontal centres and two diameters between vertical centers, or slightly more. If two bolt flanges were used, the spacing could be even less.

Itwill be seen that as water or other fluid flows through units I4 from header I6 to header I 8, the single-tube sections 2 Ia will offer more resistance to the flow per unit of length than will the `runs 20 containing a plurality of tubes such as 2I. The sections 2Ia therefore will help toprevent an unequal distribution of fluid between the different units I4 and so avoidone of the practical fdifliculties in the operation of economizers and like -heaters wherein certain units, when they are of uniform free cross section throughout, receive more than their proper share of the ifluid, thereby robbing certain other units and causing such latter units to become overheated. Of course, if

vsteam forms in any unit or group of units, such a tendency to unequal Vdistribution of water, or

other fluid to be heated, is greatly aggravated. The arrangement illustrated in which the singletube sections 2 Ia have only a fraction of the free cross sectional area of the tubes 2| with which they unite affects the design favorably in two different directions, one as to the room available for joints between tube runs and the other as to Ythe operation by promoting equal distribution of water between the units. I prefer, further, to increase the effect of the sections 2I'a as to distribution of fluid between the units I4 by making .them with somewhat thicker walls than the tube portions or sections 2I but of the same external diameter, thereby not only reducing the flow area in sections 2Ia relatively to the total area per The bends 26 and 21 may conveniently be made of the same tubing as single tube sections 2Ia so as to add to the flow restricting effect of the sections 2 Ia.. However, I do not limit myself to this.

No difficulty is experienced in removing the flanges 29 of a given unit I4 'whenever it is desired to remove part or all of such unit from flue I2. As is clear from the drawings, the flanges 29 can be unscrewed Whenever desired, because there is suilicient distance between sections 2Ia of a given unit to permit adjacent flanges 29 to pass in a given transverse plane, while the sections 2Ia of different units I4 are alternately long and short, therebythrowing the flanges 29 of adjacent units 4 into different vertical planes transverse to the units so that the flanges on adjacent units turn past each other, altho their projections on the plane of plate IIJ overlap.

The flue I2 is bounded on opposite sides by the walls I0 and Ic and I prefer to utilize such walls for sustaining a large portion of the weight of units I4. For this purpose, walls III and Ina may conveniently be made -of cast iron and made thick enough to support the weight expected to fall on them. In the average case, however, the walls IO vand Ia will be spaced a sufficient distance apart so that a considerable portion of the weight of the units I4 will need to be carried by an intermediate partition or partitions IIIb. Partitions IIlb can be of the same construction as walls ID and IIla.

The single tube sections 2 Ia pass through holes (not shown) in wall I0, one'section 2Ia in one suchv hole so that the weight of one portion of each tube run 20 is transferred to wall I0 by a vsection Zia. Invthe case of Walls I 0a and IIIb, however, a somewhat different arrangement is necessary. At the planes of such walls, the tube runs 2U of the arrangement illustrated in Figs. l, 2 and 3 are composed of three tubes 2I so that the openings through each of plates Illa and I0b for each of the tube runs 20 is preferably of a triangular shape as indicated in Figs. 2 and 3. In order to brace the tube runs at the walls IIIa and Ilib, however, and betterto -transfer the weight of the tube runs to the walls I 0a and Ib, I provide triangular plates 32, 32 .which space the tubes 2I of each tube run 20 at the planes of walls Ia and Ib and help transfer the weight of the tube runs to such walls. Of course, there are inclined webs 34 left between adjacent holes through the lwalls |0a andlb so 'that suchwalls shall not be Vunduly weakened by the `openings for the tube runs; It will be noted in Fig. A1 that the tube runs 2,0 of each unit are arranged in groups of 6, ad- -jacent groups being spaced somewhat more widely in avertioal direction than the adjacent tube runs of each group. Such spaces are provided for soot blowers and form-no part of the inven-V tion. Outer.insulating walls 35, 35 for confining the heating gasesand preventing loss of'heatby radiation l'are also shown in Figs. l, 2 andB.

The embodiment of thesinvention illustrated in Figs. 4, 5, 6, 9and 10 is similar in many respects to the embodiment already described and illusvtrated'in Figs. l', 2, 3, '7 and 8. In the arrangementV of Figl, the tube runs-20a of the unitsv led 4contain only tWo tubes 2|, 2|'v in parallel instead -of'the threetubesin parallel inthe units I4, the `plurality of tubes 2|'ineach run Zla being con'- nected toasingle tube portion 2|@V the saine as in Fig. l. The tubes 2| of each tube runV are'pref-v erably arrangedin-a horizontal plane 'as shown,l but a given tube run 20a is staggered horizontally Y 20afof a given lunit Ida, the bends 26a lie in planes V:as

at an angle to thevertical. At the ends of the lruns v'200i opposite the single tube sections 2m, the individual vtubesV 2| Vare preferably connected by Vintegral forged return bends 24a so that` adjacent runs 20a are connected together in pairs by integral bends' 24ato formY U-loops, adjacent `U-V loopsbeing connectedV in pairs by said removable return bendsZBa. The spacing oftubes2| in the arrangement shown in Figs. 4, 5 and 6 is,` in terms f tubediameters, substantially that of the corresponding tubes 2| inthe arrangement of Figs. 1,2a`nd3.:y

VWherehthe` runs 20a pass through an intermediate wall lub, the wall is cut outV to form rhomboidal openings 36 (Fig. 5) separated by webs 34a. In such openings 36 the pipes `2| of each U are spread and ,braced'by av plate 31. At each point where the' return bends Mapass through the wall Illa, the two integral bends 24a belonging toa givenunit Ma are set in a plate 38 which rests on the lower edge of an openingll in the wall Illa and is slidable thereinv to facilitate` in# sertion and removal of the runs 20a. The openings Ml are spaced by the webs 42 integral with the body of plate IliaJ so that the wall |0a is not unduly weakened by such openings. Y

'I'he return bends 26a and the associated joints between such bends andthe tube sections 2|a of units Md are illustrated onan enlarged scale vin Figs; 9.and` 10. It will be seen that the relative offsetting of adjacent runs 20a to force the gases going upor down in flue |2 of Fig.l 4 to follow a tortuouspath Yresults'in placing the bends 26a in planesinclin'ed to the vertical instead of in the vertical as inthe case4 with bends 26 andY 21 of Figs. 1 V and 2. `,In `thearrangement shown;V the triangular anges and 29associated with bends i 26a'andsections A2id respectively of Figs. 9V and 10 can. turn past. the. flanges on the units adjacent to a given unitlfbecause the unitsY are assembled with sufficientl -clearance to'permit it.` 4The. sections'v 2 lay .of tube runs. 20a .onnectedin pairsby integral bends 24a to form UsV are of different lengths r`so that the' anges on the endsi of sections 2|a of a given U can beturned.- Without interference, because they lie in differentyplanes.

Interference will occur, however, in the arrangement shown in Figs. 4, 5 and 6', between flanges on sections 2| a of adjacent Us. VWhen it is desired to remove agiven U therefore, afterv taking off the removable return bend V26a connected thereto, it is necessary to push such U longitudinally'enoughto let its ilanges clear those on the adjacent Us and they can thereupon be un` screwed and the given YU removed.

It will be seen from the drawings that designs `in accordance with my invention provide a large amount of heating vsurface per cubic footV of flue' volume without necessitating the weight and expense attendant upon the use of extended surface and at the same time` permit the use of thru bolt ange joints for the removable return bends. v

The featuresof construction and arrangement hereindisclosed are, however, well adaptedY forV use with tubes .having extendedsurface and Ymay be used with such extended surface tubes with-Y out departing. from my invention.

While I prefer to use integral bends,r alongone side or end of the unit bundle, thereby dividing the units into Us, I do not limit myself to this in all cases. 1

While I have disclosed anumber of novel fea# tures of construction and arrangement,v I, do not limit myself to the` use of all such features in a given installation.

What I claim is:` l. A heater having a flue, a plurality of serpentine units in said iiue connected for parallel `flow therethrough of fluid to beheated, eachofsaid units having substantially straight tube runs and return bends for joining said runs, each of said runs comprising ,throughout its major portion 'a group oftubes inlparallel and. each such group of tubes united near at least one of its ends Yto a single-tube section having a free cross-sectional Varea not much more than halfthe total free area of the group to which it is joined, those of said return bends along at least'one side of the heater being removable and connected directly to said single tube section.

2. ,A heater havinga flue, a plurality of serpentine units therein connected for parallel. flow therethru, each of said units having substantially straight tube runs and return bends for joining said. runs, each of said runs comprising throughout its major portion' a group of tubes in parallel and y each such group of tubes united near at least one of its'ends into asingle tube section having a free cross-sectional area 4not much more thanl half the total free area of the group to which it is joined, those ofsaid return bendsalong at least oneside of the heater being removable and rconnected directly to said single-tube sections, said sections having polygo-Y nal flanges threaded thereon and said removable Vbends, kalso having polygonal flanges thereon, said iianges adapted to be bolted` together .to` secure Vsaid removable bends in place.

3. A heater having a plurality of serpentine units connected for parallel flow of fluidftherethrough, eachof said unitsvhaving U`loops including pipe runs and integral return bends for joining said runs, and removable returnibends along one side ofthe units having polygonal' said loops so proportioned and placed that each end: section is not more than two and one-half diameters .from the end section closest to it but the polygonal flange on each of said end sections arranged to clear the end section closest to the one supporting it and alternate anges in a given direction in dilerent planes transverse to such loops whereby the flanges may be rthreaded into Dlcegwithout interference., y

4. A heater having a plurality of serpentine units connected forrparallel flow therethrough, eachof saidunits having U-loops including pipe runs and return bends for joining said runs, each of saidV loops comprising` throughout the major portion of its length a plurality of tubes in parallel and such tubes united near the ends of the loopsinto single tube sections having a free cross section not much more than half the total free cross section of thek plurality of tubes to which they are joined, removable return bends connecting the unitary tube sections o1 adjacent ends of dierent U-lcops, polygonal anges threaded on said unitary tube sections at the ends of the loopsy eomplementarypolygonal anges carried 0n the ends of said removable return bends and adapted to be bolted to the lianges on said sections, said loops having such dimensions and being so arranged that each of said unitary tube sections is spaced not more than two and onehalf diameters from the tube section closest to it, but said unitary tube sections at the ends of the loops having different lengths whereby the flanges on a given loop lie in different planes transverse to the loop to permit the flanges on its unitary `tube sections'to be threaded into place without mutual interference,

5. A heater as set forth in claim 4 and in which each of the Us comprises a relatively long section having a plurality of tubes in parallel and relatively short sections having unitary tubes joined to the plural tubes of said first mentioned sections.

6. A heater comprising serpentine units each formed of a plurality of U.loops connected by removable return bends, the major portions of said loopsI having two pipes in parallel, said loops each having their two pipes set not more than two tube diameters between horizontal centers and said units set so that the tubes of adjacent units are also not more than two tube diameters between horizontal centers, the said Us having singletube end-sections united to said two pipes, said, end sections terminating at different distances from the closed ends of the Us, and bolted-type ange joints having more than two boltsleach between 'said sections and said removable return bends.

7. A heater comprising serpentine units each formed of a plurality of U-loops connected by removable return bends, the major portion of said loops having twopipes in parallel, said loops each, having their two pipes set not vmore than two and one-half tube diameters between vertical centers and not more than two tube diameters between horizontal centers and the units set so that the tubes of the adjacent units are not more than two tube diameters between horizontal centers, the said Us having single-tube end sections united to said two pipes, said end sections terminating at different distances from the closed ends of the Us, and bolted-type flange joints having more than` two bolts each between said sections and said removable return bends.

8. A heater as set forth in claimv l and Yin which vthe single-tube end sections of the pipe runs have a greater Wall thickness than the tubes of the remaining sections of the tube runs but have no greater external diameter than such remaining sections.

9. A heater comprising serpentine units 'each formed of a plurality of U-loops connected by removable return bends, the major portions of said loops having three pipes in parallel, sa.id loopshaving their three pipes arrangedso that alternately a single pipe is at the outside of the loop and so that alternately two pipes are at` the outside of the loops, said loops having two pipes set not more than two tube diameters between horizontal centers and the units al1 set so that tubes of adjacent units are not more thantwo tube diameters between the horizontal centers, said tubes beingv so formed and said units being so arranged that none of the tubes are spaced more than two tube diameters between vertical centers, the said Us having single-tube end sections united to said three pipes in parallel, said end sections in one unit terminating at a different distance from the closed ends of the Us than in the unit on each side of said one unit, and three-bolt flange joints between said sections and said removable return bends. Y

10. A heater as set forth in claim 1, together with supporting walls lying transverse to the tube runs, the single tube end section projecting thru and resting in one of said walls and another of said walls having enlarged openings, integral bends joining the tubes at one side of the tube bundle and plates each embracing the integral bends of at least one tube run and resting in one of said openings.

l1. An economiser comprising a plurality of units in parallel, each of said units including a plurality of U-loops, each such loop having a main portion providing a plurality of pathsin parallel for fluid to be heated and having integral throats one for delivering fluid to the other for receiving fluid from said paths. Y

12. An economizer as set forth in claim l1 and in which the throat portions of the U-loops have a free internal cross sectional area less than the free area of theY plurality of paths comprised in a given U-loop. 13'. An economizer as set forthin claim l1 .and in which the throats of adjacent VUs are connected by removable return bends having free cross-sectional areas equal to those `of the throats to which they connect. l

14. An economizer as set forth in claim 11 together with plates embracing and supporting lthe throats at one end of the Us and the return bends at the opposite ends of the Us.

l5, An economizer as set forth in claim ll and in which the U-loops have two paths in parallel for rfluid to be heated and integral return bends at the closed ends of the Us, plates embracing the throats at the one Vendv of the Us, a plate having apertures into which the bends of the Us project, at the opposite endsl of the Us, and smaller plates contacting each the bends of one U vand resting in said last apertures. 16. The combination in a fluid heater of a plurality of serpentine units arranged forfow of fluid therethru in parallel, each of saidunits hav.- ing a series of removable return bends connecting portions of the unit, each of such portions having a plurality of pipes in parallel connectedstoa single pipe section whose free ow area-is less than that of said pipes in parallel'.

'17. A heater havingy a plurality-of serpentine units connected forY parallel flow of fluid there' P through, each of said units having U-loops including pipe runs and return bendsV for joining said runs, each of said loops comprising throughout the major portion of its length a plurality of tubes in parallel and such tubes united near the ends of the loop into single tube sections having free cross-section not much more than half the `total free cross section of the plurality of tubes to which they are joined, removable returnbends connecting the unitary tube sections of adjacent ends of different U-loops, polygonal flanges threaded on said/unitary tube sections at the ends of the loops,` complementary lpolygonal flanges carried on the ends of said removable return bends and adapted to be bolted to the flanges on said sections., said loops having such dimensions and being so arranged that each of said unitary tube sections is spaced not more than twoV and a half diameters from the tube section closest to it, the loops of a given unit being all of a given length While those on units on both sides of said given unit are both either longer or shorter than those of the given unit whereby the flanges on the loop of a given unit lie in a different plane lfrom those on the adjacent units to permit the anges to be threaded into place Without interference from those on the other units. i

JOHN H. SENGSTAKEN. 

